James Paroissien


James Paroissien was born in Barking, Essex in 17841, to Louis and Mary Paroissien. His great grandfather was a French Huguenot refugee, naturalized as an Englishman in 1709, and his father was a Schoolmaster in Barking.  

Having obtained his medical degree in London, in 18062, he travelled to South America in December 1806, representing British mining interests. On hearing of the failed invasion of Buenos Aires by the British Army, he remained in Montevideo, until travelling to Río de Janeiro. There he was involved with Saturnino Rodríguez Peña, a Buenos Aires citizen, in a scheme to bring out from Spain the Bourbon “Infanta” Carlota Joaquina to be installed as regent or queen in the Viceroyalty of Río de la Plata. On returning to Montevideo, he was arrested by the governor Francisco Javier de Elío, and jailed by the authorities for having committed high treason, awaiting sentence. Having the new Viceroy of the River Plate Baltasar Hidalgo de Cisneros arrived in Montevideo in 1809, on his way to Buenos Aires, he ordered that Paroissien be transferred to Buenos Aires for his trial.

Juan José Castelli undertook his defence, as his lawyer, and later, being Castelli one of the members of the ‘Junta’ following the Revolution in 1810, Paroissien was set free after 18 months in jail.  He then accompanied Castelli in the army led by Balcarce to the Alto Perú, to try to expel the powerful Spanish Army. After the disastrous defeat in Huaqui, he assisted General Pueyrredón in the evacuation of Potosí (one of the most important northern cities at the time), and in transporting the enormous riches of the city treasury out of the reach of the Spanish Army. For this, he was the first foreigner naturalized in Argentina, confirmed subsequently by the 1813 Assembly.




James (Diego) Paroissien          Army crossing of the Andes, under San Martín

He remained attached to the “Army of the North”, until his appointment as Director of the newly created gunpowder factory in Córdoba. There he met José de San Martín, and was subsequently appointed as Chief Surgeon to the Mendoza battalion of the reformed Andes Army, then under San Martín’s command. He was instrumental in caring for the leader’s health, who was afflicted by recurring stomach ulcers and bouts of arthritis during the march across the Andes, having to be transported in a litter for part of the way.

During the battle of Chacabuco in Chile, besides rendering his professional services, he was aide-de-camp to General Soler. He founded the Chilean Legion of Merit, and after the defeat at Cancha Rayada, he attended to General Bernard O’Higgins’s wounds. After the final triumph in that campaign at Maipú, an observer named Samuel Haigh left a vivid description of Dr. Paroissien’s bravery and of his surgical expertise on the battlefield.

This led him to be promoted to colonel, and to receive the Maipú Gold Medal and a large plot of land in Mendoza, for his distinguished services. In 1820 he accompanied General San Martin on his Peruvian expedition: there he was promoted to Brigadier General, and rewarded with the “Orden del Sol”, being a founding member of this Order.

General San Martín, then Protector of Perú, sent him and Juan García del Río on a diplomatic mission representing Perú, to Argentina -where they were not received- and to Europe, charged with finding an emperor for the throne of Perú. In London, for over two years they maintained a Peruvian legation, striving for the recognition of Peruvian independence, and failing in the monarchical intent. Their mission terminated on hearing of San Martín’s resignation as leader of Perú, who then headed for Europe. Starting his exile in London, there Paroissien found lodgings for the exiled General.  

He subsequently accepted the offer of the “La Paz, Potosí and Peruvian Mining Association”, a British enterprise, to manage the Potosí mines in the newly independent Bolivia. His fortune ran out shortly after: the company had to be liquidated, and after losing all his South American possessions, he was financially ruined. In failing health, he died on a sea voyage between Perú and Chile on the Olive Branch, on September 23rd, 1827, being buried in Valparaíso, Chile. He never married, and has had no descendants.

There is a Hospital in the city of Mendoza named after him, as also another Hospital in Isidro Casanova, province of Buenos Aires (Hospital General de Agudos Dr. Paroissien). A street in the city of Buenos Aires is graced with his name.

Different historical sources have suggested that from the outset of his first journey to South America he was an agent for the British government. C.L.A.M.O.R., in its Blog on James Paroissien, inferring on his probable condition as an informant for the Crown of England, reports that his collected papers were turned over by his family to the Essex Record Office, and are kept under the title of “Surgeon, Soldier, Statesman and Spy: the life of James Paroissien”.


(1)   There is some controversy in the literature about his birthdate: the years 1781, and 1783 are cited. An interested reader, Mr. Keith Neuhofer, has informed the Editor that Paroissien was born on November 15th, 1784, a fact obtained from the Select Essex Parish Registers, 1583 – 1900. This can be accessed on the Internet, at


(2)   There is also controversy as to whether he really obtained a medical diploma, as he appears never to have finished his studies in Chemistry and in Surgery, which were his main interests, and the background for his brilliant surgical feats on many battlefields.





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· England, Select Essex Parish Registers, 1583 – 1900.